Warm the tortillas. Preheat oven to 350F, then stack tortillas and wrap in aluminum foil. Place directly on oven rack and warm for about 7-10 minutes. Alternatively, wrap tortillas in a damp paper towel, then heat in a microwave in 30-second increments until warm. Place two warmed tortillas on each plate.
Whisk the eggs. Combine eggs, onion, 2 Tbsp chives, 1 tsp Kosher salt, and ¼ tsp black pepper in a mixing bowl, then whisk to combine.
Cook the eggs. Heat a large nonstick skillet over medium heat (no higher!), then coat with cooking spray. Add eggs and cook, stirring often, until small curdles form. Adjust and lower heat as needed so eggs do not brown or cook too quickly.
Stir in remaining ingredients. When eggs are slightly runny, add 6 Tbsp cubed cream cheese and ½ cup smoked salmon. Continue cooking until eggs are no longer runny, stirring often, then remove from heat.
Assemble, then serve. Divide scrambled eggs evenly between warm four tortillas, then top with additional chives. Serve immediately with lime wedges.